Synthesis of Dihydro- and Tetrahydro-1,2,4,5-tetrazines from the Reaction of Nitrilimines with 1-Substituted-1-methylhydrazine

The reaction of nitrilimines (2) with 1-substituted-1-methylhydrazines (3–6) led to the formation of the respective amidrazones (7) when R = CH3, Ph, and to the acyclic adducts (8,9) when R = CHO and COCH3. The acyclic adducts underwent thermal oxidative cyclization at CH3 to give the unexpected 1,2,4,5-tetrazines (10,11). Dihydro-l,2,4,5-tetrazines (12) were also seperated when R = CHO.